Mosquitoes may remember smells of hosts

Thinking that you may receive mosquito bites if you are sweeter may not be that far-fetched as a new study suggests that mosquitoes may abandon hosts who swat at them, according to a new study.

The study, published in the journal Current Biology, shows that mosquitoes can rapidly learn and remember the smells of hosts and that dopamine is a key mediator of this process.

Mosquitoes use this information and incorporate it with other stimuli to develop preferences for a particular vertebrate host species, and, within that population, certain individuals.

However, the study also proved that even if an individual is deemed delicious-smelling, a mosquito’s preference can shift if that person’s smell is associated with an unpleasant sensation.

According to the researchers, hosts who swat at mosquitoes or perform other defensive behaviour may be abandoned, no matter how sweet they are.

“We now know that mosquitoes are able to learn odours emitted by their host and avoid those that were more defensive,” said co-author of the study, Chloe Lahondere, Research Assistant Professor at Virginia Tech in the US.

For the study, researchers demonstrated that mosquitoes exhibit a trait known as aversive learning by training female aedes aegypti mosquitoes to associate odours (including human body odours) with unpleasant shocks and vibrations.

Twenty four hours later, the same mosquitoes were assessed in a Y-maze olfactometer in which they had to fly upwind and choose between the once-preferred human body odour and a control odour.

The mosquitoes avoided the human body odour, suggesting that they had been successfully trained, the researcher said.

By taking a multidisciplinary approach and using cutting-edge techniques, including CRISPR gene editing and RNAi, the researchers were also able to identify that dopamine is a key mediator of aversive learning in mosquitoes.